Identification of Glycinin and β-Conglycinin Subunits that Contribute to the Increased Protein Content of High-Protein Soybean Lines

Abstract

Seed protein concentration of commercial soybean cultivars calculated on a dry weight basis ranges from approximately 37 to 42% depending on genotype and location. A concerted research effort is ongoing to further increase protein concentration. Several soybean plant introductions (PI) are known to contain greater than 50% protein. These PIs are exploited by breeders to incorporate the high-protein trait into commercial North American cultivars. Currently, limited information is available on the biochemical and genetic mechanisms that regulate high-proteins. In this study, we have carried out proteomic and molecular analysis of seed proteins of LG00-13260 and its parental high-protein lines PI 427138 and BARC-6. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis revealed that the high-protein lines accumulated increased amounts of beta-conglycinin and glycinins, when compared with Williams 82. High-resolution two-dimensional electrophoresis utilizing pH 4-7 and pH 6-11 ampholytes enabled improved resolution of soybean seed proteins. A total of 38 protein spots, representing the different subunits of beta-conglycinin and glycinin, were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. High-protein was correlated with an increase in the accumulation of most of the subunits representing beta-conglycinin and glycinin. Comparisons of the amino acid profiles of high-protein soybean lines revealed that the concentration of sulfur amino acids, a reflection of protein quality, was not influenced by the protein concentration. Southern blot analysis showed the presence of genotypic variation at the DNA level between PI 427138 and BARC-6 for the genes encoding group1 glycinin, beta-conglycinin, Bowman-Birk inhibitor (BBI), and the Kunitz trypsin inhibitor (KTI). LG00-13260 inherited the allelic variants of the parental line PI 427138 for glycinin, beta-conglycinin, and KTI, while BBI was inherited from the parental line BARC-6. The results of our study indicate that high-seed protein concentration is attributed to greater accumulation of specific components of beta-conglycinin and glycinin subunits presumably mediated by preferential expression of these genes during seed development.

Subunit composition of seed storage proteins in high-protein soybean genotypes

“…Earlier studies showed that high-protein cultivars accumulated higher amounts of glycinin and β-conglycinin (Yaklich, 2001;Krishnan et al, 2007). This study confirmed this observation, except for genotypes KO5427, Table 3.…”

Soybean: For Textile Applications and Its Printing

“…So in other way of saying, soybean fiber (SPF) is natural plant-based man-made regenerated protein fiber that is produced from a blend of soybean protein and polyvinyl alcohol [9,18]. The soybean plant, its seeds and soybean protein fiber are shown in Soybeans contain great quantity of proteins, approximately 37-42%, compared to peanut (25%), milk (3.2%) and corn (10%) proteins [1,21]. Soybean proteins can be used as food, feed, textile fiber, pharmaceutical, ink, adhesive, emulsion, cleansing material and plastic [1,6,7].…”

Establishment of a Protein Reference Map for Soybean Root Hair Cells

“…However, in other studies, soybean was successfully used to identify proteins involved in the response to pathogen invasion (Mithofer et al, 2002), salt stress (Aghaei et al, 2009), flooding (Shi et al, 2008), seed germination (Xu et al, 2006b), seed development (Hajduch et al, 2005), and UV radiation . Soybean peroxisomal proteins, xylem sap, and glycinins have also been characterized by proteomics (Natarajan et al, 2006Djordjevic et al, 2007;Krishnan et al, 2007;Arai et al, 2008). A protein reference map was also developed for soybean leaves, identifying 119 proteins (Xu et al, 2006a).…”